1. Field
The present disclosure relates generally to aerial refueling, and in particular to drogues used in aerial refueling. Still, more particularly, the present disclosure relates a method and apparatus for aerial refueling using a drogue having a canopy capable of operating across different speeds.
2. Background
In-flight refueling is an important method for extending the range of aircraft traveling long distances over areas having no feasible landing or refueling points. In-flight refueling may also be referred to as air-to-air refueling. In-flight refueling is a relatively common operation for military aircraft. The aircraft providing the fuel is referred to as the tanker aircraft, and the aircraft receiving the fuel is referred to as the receiver aircraft.
This type of operation may require the aircraft to be refueled to be precisely positioned relative to the tanker aircraft maintain connection for transferring fuel between the receiver aircraft and the tanker aircraft. The requirement for precise relative spatial positioning of the two moving aircraft makes in-flight refueling a challenging operation.
Two primary systems are currently used for in-flight refueling. One system is a hose and drogue system. This system includes a refueling hose having a drogue located at one end. The hose and drogue are deployed and trail behind the tanker aircraft once the tanker aircraft is in position to deliver the fuel. The pilot of the receiver aircraft then flies the receiver aircraft to intercept and couple with the drogue for refueling.
Another existing system is a boom refueling system. The boom refueling system typically includes a rigid boom extending from the tanker aircraft, with a probe and nozzle at its distal end. The boom also includes airfoils controlled by a boom operator stationed on the refueling aircraft. The airfoils allow the boom operator to maneuver the boom with respect to the receiver aircraft, which flies in a fixed refueling position below and aft of the tanker aircraft.
Typically, drogue aerial refueling operations occur at airspeeds between around 105 knots to around 325 knots. Different drogues are designed to operate at different speeds in this range. Existing drogues can be classified as low speed, high speed, variable speed, or variable drag.
A typical low speed drogue operates around 105 to around 180 knots. A typical high speed drogue operates around 180 to around 325 knots. These different types of drogues operate with a fixed area drogue canopy that has a fixed projected frontal area. Variable speed and variable drag drogues are designed with fixed area canopies, but have limited ability to change the drogue's drag. In variable speed and variable drag drogues, the surface area of the canopy is fixed, but the projected frontal area is manipulated to change the speed in which the drogue may operate. These drogues have a broader speed range than typical low and high speed drogues. Still, the largest range of these may be from around 105 to around 230 knots. Since different canopies operate at different speeds, the drogue canopy for the tanker aircraft may need to be changed out from time to time based on the anticipated speed of refueling that may be used on the next refueling mission. The change requires time and may delay a refueling mission if the needed drogue canopy is not identified with sufficient time to make a change without delaying the mission.
Thus, it would be advantageous to have a method and apparatus that takes into account at least some of the issues discussed above, as well as possibly other issues.